Preheat the oven to 180⁰C.
Combine the garlic and butter and divide between the mushrooms, placing a small dollop in the centre of each one. Sprinkle over the rosemary, then bake the mushrooms for 20 minutes.
Meanwhile, place the onion in a small pan with a good pinch of salt. Cook for 5 minutes and then add the honey and balsamic vinegar. Continue cooking for another 5-10 minutes until nicely caramelised.
When the mushrooms and onion are nearly ready, heat a fry pan on high and add your steak. Turn down to medium and cook for 5-6minutes each side or until cooked to your liking. Allow to rest for 2-3 minutes. Meanwhile steam your beans and broccolini.
Serve the steak with the greens, garlic mushies and caramelised onion.